Electrophoretic device, display unit, and electronic apparatus

ABSTRACT

An electrophoretic device includes: a porous layer including a first fibrous structure and a non-electrophoretic particle held in the first fibrous structure; an electrophoretic particle configured to move through a space formed at the porous layer; a second fibrous structure covering the porous layer; and a partition provided from the porous layer to the second fibrous structure.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 14/085,445 filed on Nov. 20, 2013 which claims priority of theJapanese Patent Application No. JP2012-258544 filed on Nov. 27, 2012 inthe Japan Patent Office, the entire contents of which are incorporatedherein by reference.

BACKGROUND

The present technology relates to an electrophoretic device including anelectrophoretic particle in an insulating liquid. The present technologyalso relates to a display unit using the electrophoretic device, and anelectronic apparatus provided with the display unit.

In recent years, low-power display units (displays) with high imagequality have been in increasing demand, as mobile equipment such asmobile phones and portable information terminals has become widespread.In particular, recently, electronic book delivery businesses have begun,and a display having display quality suitable for reading purpose hasbeen desired.

As such a display, displays such as a cholesteric liquid crystaldisplay, an electrophoretic display, an electric-redox-type display, anda twisting ball display have been proposed. For reading purpose,reflection-type displays are advantageous. In the reflection-typedisplays, bright display is performed using reflection (diffusion) ofexternal light in a manner similar to paper and thus, display qualityclose to that of paper is achieved.

Among the reflection-type displays, an electrophoretic display utilizingan electrophoretic phenomenon has a high response speed while consuminglow power, and thus is expected as a strong candidate. As a displaymethod thereof, mainly the following two methods have been proposed.

A first method is a method in which two kinds of charged particles aredispersed in an insulating liquid, and the charged particles are movedin response to an electric field. These two kinds of charged particlesare different from each other in terms of optical reflection property,and are also of opposite polarity. In this method, an image is displayedby changing of distribution of the charged particles in response to anelectric field.

A second method is a method in which charged particles are dispersed inan insulating liquid, and a porous layer is disposed (for example, seeJapanese Unexamined Patent Application Publication No. 2012-22296). Inthis method, the charged particles are moved through pores of the porouslayer in response to an electric field. For example, a polymeric filmmay be used for the porous layer.

SUMMARY

Although various display methods such as those described above have beenproposed for the electrophoretic display, the display quality thereof isstill insufficient, and a further improvement in contrast is expected.

It is desirable to provide an electrophoretic device, a display unit,and an electronic apparatus that are of high contrast.

According to an embodiment (1) of the present technology, there isprovided an electrophoretic device including: a porous layer including afirst fibrous structure and a non-electrophoretic particle held in thefirst fibrous structure; an electrophoretic particle configured to movethrough a space formed at the porous layer; a second fibrous structurecovering the porous layer; and a partition provided from the porouslayer to the second fibrous structure.

According to an embodiment (2) of the present technology, there isprovided an electrophoretic device including: a porous layer including afibrous structure and a non-electrophoretic particle held in the fibrousstructure; an electrophoretic particle configured to move through aspace formed at the porous layer; and a partition provided from insideof the porous layer to outside of the porous layer. A width of a part ofthe partition, the part being on the outside of the porous layer, issmaller than a width of a part of the partition in the porous layer, thepart being closest to the outside.

According to an embodiment (3) of the present technology, there isprovided a display unit provided with an electrophoretic device. Theelectrophoretic device includes: a porous layer including a firstfibrous structure and a non-electrophoretic particle held in the firstfibrous structure; an electrophoretic particle configured to movethrough a space formed at the porous layer, a second fibrous structurecovering the porous layer, and a partition provided from the porouslayer to the second fibrous structure.

According to an embodiment (4) of the present technology, there isprovided a display unit provided with an electrophoretic device. Theelectrophoretic device includes: a porous layer including a fibrousstructure and a non-electrophoretic particle held in the fibrousstructure, an electrophoretic particle configured to move through aspace formed at the porous layer; and a partition provided from insideof the porous layer to outside of the porous layer. A width of a part ofthe partition, the part being on the outside of the porous layer, issmaller than a width of a part of the partition in the porous layer, thepart being closest to the outside.

According to an embodiment (5) of the present technology, there isprovided an electronic apparatus with a display unit. The display unitis provided with an electrophoretic device. The electrophoretic deviceincludes: a porous layer including a first fibrous structure and anon-electrophoretic particle held in the first fibrous structure; anelectrophoretic particle configured to move through a space formed atthe porous layer, a second fibrous structure covering the porous layer,and a partition provided from the porous layer to the second fibrousstructure.

According to an embodiment (6) of the present technology, there isprovided an electronic apparatus with a display unit. The display unitis provided with an electrophoretic device. The electrophoretic deviceincludes: a porous layer including a fibrous structure and anon-electrophoretic particle held in the fibrous structure; anelectrophoretic particle configured to move through a space formed atthe porous layer, and a partition provided from inside of the porouslayer to outside of the porous layer. A width of a part of thepartition, the part being on the outside of the porous layer, is smallerthan a width of a part of the partition in the porous layer, the partbeing closest to the outside.

In the electrophoretic device according to the embodiment (1) of thepresent technology, the porous layer including the non-electrophoreticparticle is covered with the second fibrous structure. Therefore, lightapplied to a surface (a surface on the second fibrous structure side) isprevented from being affected by the non-electrophoretic particle. Thisallows, for example, a width of the partition in the second fibrousstructure to be smaller than a width in the porous layer, when thepartition is formed using a photocurable resin. In the electrophoreticdevice according to the embodiment (2) of the present technology, awidth of the part of the partition, the part being on the outside of theporous layer, is made smaller than a width thereof in the porous layer.Therefore, a region between the adjacent partitions is widened on thesurface side (on the outside of the porous layer). In other words, aregion in which the electrophoretic particle is freely movable becomeslarge.

According to the electrophoretic device, display unit, and electronicapparatus of the above-described embodiments (1), (3), and (5) of thepresent technology, the porous layer is covered with the second fibrousstructure. According to the electrophoretic device, display unit, andelectronic apparatus of the above-described embodiments (2), (4), and(6) of the present technology, the width of the part of the partition,the part being on the outside of the porous layer, is smaller than thewidth in the porous layer. Therefore, a region in which opticalcharacteristics change due to electrophoresis is allowed to be large.Accordingly, it is possible to improve contrast of a displayed image.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, and are intended toprovide further explanation of the technology as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the present disclosure, and are incorporated in andconfigure a part of this specification. The drawings illustrateembodiments and, together with the specification, serve to describe theprinciples of the technology.

FIG. 1 is a cross-sectional diagram illustrating a configuration of adisplay unit according to an embodiment of the present technology.

FIG. 2 is a plan view illustrating a configuration of an electrophoreticdevice illustrated in FIG. 1.

FIG. 3A is a cross-sectional diagram illustrating a configuration of apartition illustrated in FIG. 1.

FIG. 3B is a plan view illustrating a configuration of the partitionillustrated in FIG. 1.

FIG. 4A is a cross-sectional diagram illustrating an example of aprocess of manufacturing the display unit illustrated in FIG. 1.

FIG. 4B is a cross-sectional diagram illustrating a process followingthe process in FIG. 4A.

FIG. 4C is a cross-sectional diagram illustrating a process followingthe process in FIG. 4B.

FIG. 5A is a cross-sectional diagram illustrating a process followingthe process in FIG. 4C.

FIG. 5B is a cross-sectional diagram illustrating a process followingthe process in FIG. 5A.

FIG. 6A is a cross-sectional diagram illustrating a process ofmanufacturing a display unit according to a comparative example.

FIG. 6B is a cross-sectional diagram illustrating a process followingthe process in FIG. 6A.

FIG. 7A is a cross-sectional diagram illustrating a configuration of apartition illustrated in FIG. 6B.

FIG. 7B is a plan view illustrating a configuration of the partitionillustrated in FIG. 7A.

FIG. 8 is a cross-sectional diagram used to describe operation of thedisplay unit illustrated in FIG. 1.

FIG. 9A is a perspective view illustrating an appearance of anapplication example 1.

FIG. 9B is a perspective view illustrating another example of anelectronic book illustrated in FIG. 9A.

FIG. 10 is a perspective view illustrating an appearance of anapplication example 2.

FIG. 11 is a perspective view illustrating an appearance of anapplication example 3.

FIG. 12A is a perspective view illustrating an appearance of anapplication example 4 when viewed from front.

FIG. 12B is a perspective view illustrating an appearance of theapplication example 4 when viewed from back.

FIG. 13 is a perspective view illustrating an appearance of anapplication example 5.

FIG. 14 is a perspective view illustrating an appearance of anapplication example 6.

FIG. 15A is a diagram illustrating a front view, a left-side view, aright-side view, and a top view of an application example 7 in a closedstate.

FIG. 15B is a diagram illustrating a front view and a side view of theapplication example 7 in an open state.

DETAILED DESCRIPTION

An embodiment of the present technology will be described below indetail with reference to the drawings. It is to be noted that thedescription will be provided in the following order.

1. Embodiment (a display unit: an example that includes anelectrophoretic device including a second fibrous structure)

2. Application Examples 3. Example EMBODIMENT

FIG. 1 illustrates a cross-sectional configuration of a display unit (adisplay unit 1) according to an embodiment of the present technology.The display unit 1 is an electrophoretic display that displays an imageby utilizing an electrophoretic phenomenon. The display unit 1 includesan electrophoretic device 30 between a drive substrate 10 and a countersubstrate 20. A space between the drive substrate 10 and the countersubstrate 20 is formed by a spacer 40, and an image is displayed on thecounter substrate 20 side. It is to be noted that FIG. 1 schematicallyillustrates a configuration of the display unit 1, and the actual sizeand shape thereof may be different from those illustrated therein.

The electrophoretic device 30 is applicable to various uses. Although acase in which the electrophoretic device 30 is applied to the displayunit 1 will be described here, the configuration of the display unit 1is one example, and is modifiable as appropriate. Further, theelectrophoretic device 30 may be used for anything other than a displayunit, and the application thereof is not limited in particular.

The drive substrate 10 may include, for example, a TFT (Thin FilmTransistor) 12, a protective layer 13, and a pixel electrode 14 in thisorder, on one surface of a supporting member 11. The TFT 12 and thepixel electrode 14 may be arranged in a matrix or segmented,corresponding to a pixel arrangement.

The supporting member 11 may be configured of, for example, any of aninorganic material, a metallic material, a plastic material, and thelike which are plate-shaped. Examples of the inorganic material mayinclude silicon (Si), silicon oxide (SiOX), silicon nitride (SiNX), andaluminum oxide (AlOx). Examples of the silicon oxide may include glassand spin-on-glass (SOG). Examples of the metallic material may includealuminum (Al), nickel (Ni), and stainless steel. Examples of the plasticmaterial may include polycarbonate (PC), polyethylene terephthalate(PET), polyethylene naphthalate (PEN), and polyethyl ether ketone(PEEK).

In the display unit 1, an image is displayed on the counter substrate 20side and thus, the supporting member 11 may be opticallynon-transparent. The supporting member 11 may be configured of a rigidsubstrate such as a wafer, or may be configured of a thin-layer ofglass, a film, or the like having flexibility. The display unit 1 thatis flexible (foldable) is achievable by using a flexible material forthe supporting member 11.

The TFT 12 is a switching device used to select a pixel. The TFT 12 maybe an inorganic TFT using an inorganic semiconductor layer as a channellayer, or may be an organic TFT using an organic semiconductor layer asa channel layer. The protective layer 13 may be made of, for example, aninsulating resin material such as polyimide, and flattens the surface ofthe supporting member 11, on which surface the TFT 12 is provided. Thepixel electrode 14 may be formed of, for example, a conductive materialsuch as gold (Au), silver (Ag), copper (Cu), aluminum (Al), an aluminumalloy, and Indium Tin Oxide (ITO). The pixel electrode 14 may beconfigured using two or more kinds of conductive materials. The pixelelectrode 14 is connected to the TFT 12 through a contact hole (notillustrated) provided in the protective layer 13.

Between the drive substrate 10 and the electrophoretic device 30, abonding layer (or an adhesive layer) 15 and a sealing layer 16 areprovided. The bonding layer 15 is provided to bond the drive substrate10 and the sealing layer 16 together, and may be configured of, forexample, acrylic-based resin or urethane-based resin. A rubber-basedadhesive sheet may be used for the bonding layer 15. The sealing layer16 is provided to seal an insulating liquid (an insulating liquid 31 tobe described later) in the electrophoretic device 30, and also toprevent entering of moisture and the like into the electrophoreticdevice 30. The sealing layer 16 may be configured of, for example,acrylic-based resin, urethane-based resin, a rubber-based adhesivesheet, or the like.

The counter substrate 20 may include, for example, a supporting member21 and a counter electrode 22. The counter electrode 22 is provided on awhole surface (a surface facing the drive substrate 10) of thesupporting member 21. The counter electrode 22 may be arranged in amatrix or segmented, in a manner similar to the pixel electrode 14.

A material similar to that of the supporting member 11 may be used forthe supporting member 21, as long as the material is opticallytransparent. For example, a translucent conductive material (atransparent electrode material) such as Indium Tin Oxide (ITO), AntimonyTin Oxide (ATO), Fluorine doped Tin Oxide (FTO), and Aluminum Zinc Oxide(AZO) may be used for the counter electrode 22.

The electrophoretic device 30 is to be viewed through the counterelectrode 22. Therefore, the optical transparency (transmittance) of thecounter electrode 22 may be preferably as high as possible, and may be,for example, about 80% or more. In addition, preferably, the electricalresistance of the counter electrode 22 may be as low as possible, andmay be, for example, about 100Ω/□ or less.

The electrophoretic device 30 causes contrast by utilizing anelectrophoretic phenomenon. An electrophoretic particle 32, a porouslayer 33, a partition 34, and a second fibrous structure 37 are includedin the insulating liquid 31.

The insulating liquid 31 fills a space surrounded by the drive substrate10 (the sealing layer 16), the counter substrate 20, and the spacer 40,and may be configured of, for example, an organic solvent such asparaffin and isoparaffin. For the insulating liquid 31, one kind oforganic solvent may be used, or two or more kinds of organic solventsmay be used. A viscosity and a refractive index of the insulating liquid31 may be preferably as low as possible. When the viscosity of theinsulating liquid 31 is made low, mobility (a response speed) of theelectrophoretic particle 32 improves. Further, energy (powerconsumption) necessary for movement of the electrophoretic particle 32becomes low accordingly. When the refractive index of the insulatingliquid 31 is lowered, a difference in refractive index between theinsulating liquid 31 and the porous layer 33 grows, which increasesoptical reflectance of the porous layer 33. The refractive index of theinsulating liquid 31 may be, for example, about 1.48.

For example, a coloring agent, a charge control agent, a dispersionstabilizer, a viscosity modifier, a surfactant, a resin, or the like maybe added to the insulating liquid 31.

The electrophoretic particle 32 dispersed in the insulating liquid 31 isone or more charged particles (electrophoretic particles), and theelectrophoretic particle 32 thus charged moves between the pixelelectrode 14 and the counter electrode 22 in response to an electricfield. The electrophoretic particle 32 has any optical reflectionproperties (optical reflectance), and contrast is caused by a differencebetween optical reflectance of the electrophoretic particle 32 andoptical reflectance of the porous layer 33. In the display unit 1, theoptical reflectance of the electrophoretic particle 32 is lower thanthat of the porous layer 33, and dark display is performed by theelectrophoretic particle 32, while bright display is performed by theporous layer 33.

Therefore, when the electrophoretic device 30 is viewed from outside,the electrophoretic particle 32 may be visually recognized as, forexample, black or a color close to black. Such a color of theelectrophoretic particle 32 is not limited in particular, as long as thecolor is capable of causing the contrast.

The electrophoretic particle 32 may be configured of, for example, aparticle (powder) of a material such as an organic pigment, an inorganicpigment, a dye, a carbon material, a metallic material, a metal oxide,glass, and a polymer material (resin). Of these, any one kind or two ormore kinds may be used for the electrophoretic particle 32. Theelectrophoretic particle 32 may also be a crushed particle or a capsuleparticle of a resin solid content including the above-describedparticle. It is to be noted that materials equivalent to theabove-listed carbon material, metallic material, metal oxide, glass, andpolymer material are excluded from materials equivalent to theabove-mentioned organic pigment, inorganic pigment, and dye.

Examples of the organic pigment may include azo pigments, metal complexazo pigments, polycondensation azo pigments, flavanthrone pigments,benzimidazolone pigments, phthalocyanine pigments, quinacridonepigments, anthraquinone pigments, perylene pigments, perinone pigments,anthrapyridine pigments, pyranthrone pigments, dioxazine pigments,thioindigo pigments, isoindolinone pigments, quinophthalone pigments,and indanthrene pigments. Examples of the inorganic pigment may includehydrozincite, antimony white, black iron oxide, titanium boride, redoxide, mapico yellow, minium, cadmium yellow, zinc sulphide, lithopone,barium monosulfide, cadmium selenide, calcium carbonate, barium sulfate,lead chromate, lead sulfate, barium carbonate, white lead, and aluminawhite. Examples of the dye may include nigrosine dyes, azo dyes,phthalocyanine dyes, quinophthalone dyes, anthraquinone dyes, andmethine dyes. Examples of the carbon material may include carbon black.Examples of the metallic material may include gold, silver, and copper.Examples of the metal oxide may include titanium oxide, zinc oxide,zirconium oxide, barium titanate, potassium titanate, copper-chromiumoxide, copper-manganese oxide, copper-iron-manganese oxide,copper-chromium-manganese oxide, and copper-iron-chromium oxide.Examples of the polymer material may include a high molecular compoundinto which a functional group having an optical absorption spectrum in avisible light region is introduced. As long as such a high molecularcompound having the optical absorption spectrum in the visible lightregion is adopted, the kind thereof is not limited in particular.

Specifically, for example, the carbon material such as carbon black, themetal oxide such as copper-chromium oxide, copper-manganese oxide,copper-iron-manganese oxide, copper-chromium-manganese oxide, andcopper-iron-chromium oxide, or the like may be used for theelectrophoretic particle 32 performing dark display. Above all,preferably, the carbon material may be used for the electrophoreticparticle 32. The electrophoretic particle 32 made of the carbon materialexhibits superior chemical stability, mobility, and a light absorptionproperty.

The content (density) of the electrophoretic particle 32 in theinsulating liquid 31 is not limited in particular, but may be, forexample, about 0.1 wt % to about 10 wt %. In this density range,shieldability and mobility of the electrophoretic particle 32 aresecured. Specifically, when the content of the electrophoretic particle32 is below 0.1 wt %, shielding (concealment) of the porous layer 33 bythe electrophoretic particle 32 may be difficult, and contrast may notbe sufficiently produced. On the other hand, when the content of theelectrophoretic particle 32 is above 10 wt %, dispersibility of theelectrophoretic particle 32 may decrease, making the electrophoreticparticle 32 move less easily, thereby leading to a possibility ofoccurrence of agglomeration.

Preferably, the electrophoretic particle 32 may be readily dispersed andcharged in the insulating liquid 31 for a long time, while being lesseasily adsorbed on the porous layer 33. Therefore, for example, adispersant or an electric charge modifier may be added to theelectrophoretic particle 32. The dispersant and the electric chargemodifier may be used together.

The dispersant or the electric charge modifier may have, for example,either positive charges or negative charges, or both types of charges.The dispersant or the electric charge modifier is provided to increasean electric charge amount in the insulating liquid 31, and to dispersethe electrophoretic particle 32 by electrostatic repulsion. Examples ofsuch a dispersant may include the Solsperse series available from TheLubrizol Corporation, the BYK series as well as the Anti-Terra seriesavailable from BYK-Chemie GmbH, and the Span series available from ICIAmericas Inc.

In order to improve dispersibility of the electrophoretic particle 32, asurface treatment may be applied to the electrophoretic particle 32.Examples of the surface treatment may include a rosin treatment, asurfactant treatment, a pigment derivative processing, a coupling agenttreatment, a graft polymerization treatment, and a microencapsulationtreatment. In particular, any of the graft polymerization treatment, themicroencapsulation treatment, and a combination of these treatmentsmakes it possible to maintain long-term dispersion stability of theelectrophoretic particle 32.

Used for the surface treatment may be, for example, a material thatincludes a functional group capable of being adsorbed on the surface ofthe electrophoretic particle 32 and a polymeric functional group(namely, an adsorptive material). The functional group capable of beingadsorbed is determined according to the material forming theelectrophoretic particle 32. For example, an aniline derivative such as4-vinyl aniline when the electrophoretic particle 32 is configured ofthe carbon material such as carbon black, and an organosilane derivativesuch as methacrylate-3-(trimethoxysilyl)propyl when the electrophoreticparticle 32 is configured of the metal oxide, may be allowed to beadsorbed. Examples of the polymeric functional group may include a vinylgroup, an acrylic group, and a methacryl group.

A surface treatment may be performed by introducing a polymericfunctional group onto the surface of the electrophoretic particle 32,and causing graft thereon (namely, a graft material). The graft materialhas a polymeric functional group and a functional group for dispersion.The functional group for dispersion disperses the electrophoreticparticle 32 in the insulating liquid 31, and maintains dispersibility bysteric hindrance thereof. When the insulating liquid 31 is, for example,paraffin, a branched-alkyl group or the like may be used as thefunctional group for dispersion. Examples of the polymeric functionalgroup may include a vinyl group, an acrylic group, and a methacrylgroup. In order to cause polymerization and graft of the graft material,a polymerization initiator such as azobisisobutyronitrile (AIBN), forexample, may be used.

For reference, details of a way of dispersing the electrophoreticparticle 32 in the insulating liquid 31 as described above are describedin books such as “Dispersion technology of ultrafine particles andevaluation thereof: surface treatment and fine grinding, as well asdispersion stability in air/liquid/polymer (Science & Technology Co.,Ltd.)”.

The porous layer 33 is capable of shielding the electrophoretic particle32. The porous layer 33 includes a first fibrous structure 33A and anon-electrophoretic particle 33B held in the first fibrous structure 33Aas illustrated in FIG. 2.

The porous layer 33 is a three-dimensional structure formed using thefirst fibrous structure 33A (an irregular network structure such as anonwoven fabric), and has a plurality of clearances (pores 35). Byconfiguring the three-dimensional structure of the porous layer 33through use of the first fibrous structure 33A, it is possible to ensurethat the pore 35 has a size large enough to allow movement of theelectrophoretic particle 32, and it is also possible to maintain highcontrast even when the porous layer 33 has a small thickness.Specifically, diffused reflection (multiple scattering) of light(external light) is caused by the three-dimensional structure of theporous layer 33, and the optical reflectance of the porous layer 33increases. Therefore, it is possible to obtain high optical reflectanceeven when the thickness of the porous layer 33 is small. In addition,through use of the first fibrous structure 33A, an average pore size ofthe pores 35 is made large, and a large number of pores 35 are providedin the porous layer 33. This makes the electrophoretic particle 32 movemore easily through the pores 35, increases a response speed, andfurther reduces energy necessary to move the electrophoretic particle32. The thickness (in a Z direction) of the porous layer 33 describedabove may be, for example, about 5 μm to about 100 μm.

The first fibrous structure 33A is a fibrous substance having a lengththat is sufficiently long relative to a fiber diameter (a diameter). Forexample, a plurality of first fibrous structures 33A may gather and bestacked at random, to configure the porous layer 33. The single firstfibrous structure 33A may be twisted at random to configure the porouslayer 33. Alternatively, the porous layer 33 configured of the singlefirst fibrous structure 33A and the porous layer 33 configured of theplurality of first fibrous structures 33A may be mixed. FIG. 2illustrates a case in which the porous layer 33 is configured of theplurality of first fibrous structures 33A.

The first fibrous structure 33A may be configured of, for example, apolymer material, an inorganic material, or the like. Examples of thepolymer material may include nylon, polylactic acid, polyamide,polyimide, polyethylene terephthalate, polyacrylonitrile,polyethyleneoxide, polyvinylcarbazole, polyvinyl chloride, polyurethane,polystyrene, polyvinyl alcohol, polysulfone, polyvinylpyrrolidone,polyvinylidene fluoride, polyhexafluoropropylene, cellulose acetate,collagen, gelatin, chitosan, and copolymers of these materials. Examplesof the inorganic material may include titanium oxide. The polymermaterial may be preferably used for the first fibrous structure 33A.This is because the polymer material is low in reactivity to light andthe like, and chemically stable. In other words, use of the polymermaterial prevents an unintended decomposition reaction of the fibrousstructure 33A. When the fibrous structure 33A is configured of amaterial with high reactivity, preferably, the surface thereof may becoated with any protective layer.

The first fibrous structure 33A may, for example, extend linearly. Thefirst fibrous structure 33A may have any shape, and may be, for example,curled or bent at some point. Alternatively, the first fibrous structure33A may be branched at some point, or may be wavy. When the firstfibrous structures 33A having wavy shapes are intertwined with eachother, the structure of the porous layer 33 is made complicated, whichallows an improvement in optical property.

An average fiber diameter of the first fibrous structure 33A may be, forexample, preferably, about 1 nm or more and about 10,000 nm or less, andin particular, about 1 nm or more and about 100 nm or less. A method offorming a porous layer using cellulose, velvet, or the like has beenproposed (see, for example. Japanese Examined Patent Publication No.S50-15120). However, their refractive indexes are close to that of aninsulating liquid, and contrast may decrease. In addition, the fiberdiameter of each of cellulose and velvet is about 10 μm to about 100 μm,which is large. In contrast, making the average fiber diameter small asdescribed above makes the diffused reflection of light more easilyoccur, and also makes the aperture of the pore 35 large. The fiberdiameter is determined so that the first fibrous structure 33A isallowed to hold the non-electrophoretic particle 33B. It may be possibleto measure the average fiber diameter through, for example, microscopyusing a scanning electron microscope or the like. The average length ofthe first fibrous structure 33A is optional. The first fibrous structure33A may be formed by, for example, a phase separation method, a phaseinversion method, an electrostatic (electric field) spinning method, amelt spinning method, a wet spinning method, a dry spinning method, agel spinning method, a sol-gel method, a spray coating method, or thelike. Use of any of these methods makes it possible to easily and stablyform the first fibrous structure 33A having a length that issufficiently long relative to the fiber diameter.

The first fibrous structure 33A may be configured of preferably ananofiber. Here, the nanofiber is a fibrous substance having a fiberdiameter of about 1 nm to about 100 nm, and having a length hundredtimes or more the fiber diameter. Use of such a nanofiber for the firstfibrous structure 33A makes the diffused reflection of light easilyoccur and increases the optical reflectance of the porous layer 33further. In other words, it is possible to enhance the contrast of theelectrophoretic device 30. In addition, in the first fibrous structure33A made of the nanofiber, a ratio of the pores 35 occupying a unitvolume is made large, and the movement of the electrophoretic particle32 through the pore 35 is made easy. Therefore, it is possible to reduceenergy necessary for the movement of the electrophoretic particle 32.The first fibrous structure 33A made of the nanofiber may be preferablyformed by an electrostatic spinning method. Use of the electrostaticspinning method makes it possible to form the first fibrous structure33A having a small fiber diameter, easily and stably.

For the first fibrous structure 33A, a structure whose opticalreflectance is higher than the optical reflectance of theelectrophoretic particle 32 may be preferably used. This makes it easyto form contrast by a difference in optical reflectance between theporous layer 33 and the electrophoretic particle 32. When the firstfibrous structure 33A does not substantially affect the opticalreflectance of the porous layer 33, in other words, when the opticalreflectance of the porous layer 33 is determined by thenon-electrophoretic particle 33B, the first fibrous structure 33Aexhibiting optical transparency (colorlessness and transparency) in theinsulating liquid 31 may be used.

The pore 35 is configured by overlaps among the plurality of firstfibrous structures 33A, or twists of the single first fibrous structure33A. The pore 35 may preferably have a largest possible average poresize, to allow easy movement of the electrophoretic particle 32 throughthe pore 35. The average pore size of the pore 35 may be, for example,about 0.1 μm to about 10 μm.

The non-electrophoretic particle 33B is fixed to the first fibrousstructure 33A, and is one or more particles that are notelectrophoresed. The non-electrophoretic particle 33B may be buried inthe first fibrous structure 33A holding the non-electrophoretic particle33B, or may be partially exposed from the first fibrous structure 33A.

A material having optical reflectance different from that of theelectrophoretic particle 32, specifically, a material having higheroptical reflectance is used for the non-electrophoretic particle 33B.The non-electrophoretic particle 33B may be configured using a materialsimilar to that of the electrophoretic particle 32 described above.Specifically, metal oxide or the like such as titanium oxide, zincoxide, zirconium oxide, barium titanate, and potassium titanate may bepreferably used for the non-electrophoretic particle 33B to performbright display. This makes it possible to obtain superior chemicalstability, fixity, and light reflectivity. The non-electrophoreticparticle 33B and the electrophoretic particle 32 may be configured ofthe same material or different materials. The non-electrophoreticparticle 33B may be visually recognized from outside as, for example,white or a color close to white.

Between the porous layer 33 and the counter substrate 20 (a displaysurface), the second fibrous structure 37 is provided. The secondfibrous structure 37 is a three-dimensional structure as with the firstfibrous structure 33A, and covers the porous layer 33. The secondfibrous structure 37 does not hold any non-electrophoretic particle, andmay preferably exhibit high optical transparency in the insulatingliquid 31. Providing the second fibrous structure 37 as described abovemakes it possible to improve the contrast.

A difference between the refractive index of the insulating liquid 31and the refractive index of the second fibrous structure 37 may bepreferably smaller than a difference between the refractive index of theinsulating liquid 31 and the refractive index of the first fibrousstructure 33A. The difference between the refractive index of theinsulating liquid 31 and the refractive index of the second fibrousstructure 37 may be, for example, about 0.02 or less (from about −0.02to about +0.02), and the refractive index of the second fibrousstructure 37 may be, for example, about 1.4 to about 1.5. A materialsimilar to that of the above-described first fibrous structure 33A maybe used for the second fibrous structure 37.

In a case in which the second fibrous structure is not provided, theelectrophoretic particle is taken into the pore of the first fibrousstructure (the porous layer) on the counter substrate side when darkdisplay is performed. In other words, on the counter substrate (thedisplay surface) side, the porous layer having high optical reflectanceis partially exposed, and it is difficult to reduce the opticalreflectance of the dark display sufficiently. In contrast, when thesecond fibrous structure 37 is provided, the electrophoretic particle 32after moving to the counter substrate 20 side is taken into the pore 35of the second fibrous structure 37 closer to the display surface,thereby shielding the porous layer 33 effectively. Therefore, the secondfibrous structure 37 reduces the optical reflectance at the time of darkdisplay, making it possible to enhance the contrast. The second fibrousstructure 37 may have a thickness of, for example, about 1 μm to about 5μm.

The partition 34 is provided to partition off a space where theelectrophoretic particle 32 is present in the insulating liquid 31 (acell 36). The partition 34 extends in a lamination direction (a Zdirection) of the drive substrate 10 and the counter substrate 20 fromthe porous layer 33 to the second fibrous structure 37 to passtherethrough. One end and the other end of the partition 34 are incontact with the sealing layer 16 and the counter electrode 22,respectively. The partition 34 as described above makes it possible toprevent the electrophoretic particle 32 from moving between the cells36. Therefore, it is possible to improve image quality, by suppressingoccurrence of display unevenness due to diffusion, convection,agglomeration, and the like of the electrophoretic particles 32. Thepartitions 34 may preferably have the same heights (in the Z direction).Providing the partitions 34 having the same heights allows a distance (agap) between the sealing layer 16 and the counter electrode 22 to bekept uniform on the entire surface, thereby keeping field intensityconstant. Thus, nonuniformity of the response speed is resolved. Theheight of the partition 34 may be, for example, about 1 μm to about 100μm.

As illustrated in FIG. 3A, the partition 34 has a width (a distance inan X direction) W1 in the second fibrous structure 37, and widths W2 andW3 in the porous layer 33. The width W2 is a width of a part of thepartition 34 in the porous layer 33, the part being closest to thesecond fibrous structure 37. The width W3 is a width of a part of thepartition 34, the part being farthest from the second fibrous structure37. In the present embodiment, the width W1 of the partition 34 in thesecond fibrous structure 37 is smaller than the width W2 in the porouslayer 33. Thus, a region (an opening section) between the partitions 34next to each other in the second fibrous structure 37 (on the displaysurface side) is larger than that in the porous layer 33, which makes itpossible to improve the contrast. The width W1 of the partition 34 maybe preferably smaller than the width W3. The widths W may be the same ormay vary in the second fibrous structure 37. The width W2 and the widthW3 may be the same or may be different from each other. For example, thewidth W1 may be about 5 μm to about 10 μm, the width W2 may be about 10μm to about 20 μm, and the width W3 may be about 10 μm to about 30 μm.

The partition 34 may have, for example, a narrowed section 34C where thewidth of the partition 34 is smallest in the porous layer 33. The widthW1 in the second fibrous structure 37 may be preferably smaller than thewidth of the narrowed section 34C. In other words, the width W1 of thepartition 34 in the second fibrous structure 37 may be preferablysmaller than any of the widths (the widths W2 and W3, as well as thenarrowed section 34C) in the porous layer 33.

As illustrated in FIG. 3B, the partition 34 is provided to configure thecell 36 having a regular hexagonal shape (a honeycomb structure). Thecell 36 may have any shape, and may be, for example, rectangular. Theplurality of cells 36 may be preferably arranged in a matrix (a pluralof rows by a plurality of columns). A distance between the partitions 34next to each other along one direction (a pitch of the partitions 34)may be, for example, about 50 μm to about 500 μm.

The partition 34 extends in the porous layer 33 as described above, andpreferably, the partition 34 may support the porous layer 33. This makesa change in the position of the porous layer 33 in the insulating liquid31 less easily occur, even when the display unit 1 is left in a sidewaysposition or an inverted position for a long time. Therefore, contrastcharacteristics are allowed to be stabilized. Here, the position of theporous layer 33 refers to a positional relationship (a distance or thelike) of the pixel electrode 14 and the counter electrode 22 relative tothe porous layer 33.

The partition 34 may preferably include a light transmissive material,and also incorporate a part of the porous layer 33. Here, “incorporate apart of the porous layer 33” refers to a situation in which, while astate of holding the non-electrophoretic particle 33B in the fibrousstructure 33A (the configuration of the porous layer 33 itself) ismaintained, a part of the porous layer 33 is directly contained insidethe partition 34.

A method of providing a partition in an electrophoretic device has beenproposed (for example, Japanese Unexamined Patent ApplicationPublication (Published Japanese Translation of PCT Application) No.2003-526817). However, optical reflectance of this partition is setbetween optical reflectance of a porous layer and that of anelectrophoretic particle, and contrast is reduced by the existence ofthe partition. In contrast, the partition 34 is configured of the lighttransmissive material and also incorporates the part of the porous layer33 and thus, it is possible to prevent a decline in the contrast.Specifically, it is possible to suppress light reflection or lightabsorption due to the partition 34, because the partition 34 includesthe light transmissive material. Further, the non-electrophoreticparticle 33B included in the partition 34 causes diffused reflection oflight to increase the optical reflectance at the time of bright display,because the partition 34 incorporates the part of the porous layer 33.Therefore, it is possible to improve the contrast.

The partition 34 may include, for example, a photosensitive resinmaterial as the light transmissive material. Use of the photosensitiveresin material makes it possible to readily and stably form thepartition 34 incorporating the part of the porous layer 33. Thephotosensitive resin material may be a resin in which optical patterningis possible, some examples of which may include photocurable resins of aphotocrosslinking reaction type, a photomodification type, aphotopolymerization reaction type, and a photodegradation reaction type.The partition 34 may be configured of one kind of photosensitive resinmaterial, or may include two or more kinds of photosensitive resinmaterials. It is possible to prevent the partition 34 from affecting anelectrophoretic phenomenon of the electrophoretic particle 32, by using,for example, a chemically stable photoresist as the photosensitive resinmaterial. The photoresist may be of either of a negative type and apositive type. A light source used to pattern the photosensitive resinmay be of any type. Usable examples of the light source may include asemiconductor laser, an excimer laser, an electron beam, an ultravioletray, a metal-halide lamp, and a high-pressure mercury-vapor lamp.

The spacer 40 may be configured of, for example, an insulating materialsuch as a polymer material, and be provided, for example, in a gridbetween the drive substrate 10 and the counter substrate 20. Forexample, a sealant including fine particles may also be used for thespacer 40. An arrangement shape of the spacer 40 is not limited inparticular, but may be preferably provided to distribute theelectrophoretic particles 32 uniformly, without disturbing the movementof the electrophoretic particles 32. The spacer 40 may have, forexample, a thickness of about 10 μm to about 100 μm, and may bepreferably as thin as possible. This makes it possible to suppress powerconsumption.

The display unit 1 as described above may be manufactured by, forexample, the following procedures (FIG. 4A to FIG. 5B).

First, after the counter substrate 20 is formed by providing the counterelectrode 22 on one surface of the supporting member 21, the secondfibrous structure 37 is formed on the counter electrode 22 (FIG. 4A).The counter electrode 22 may be formed using an existing method such asvarious film forming methods. The second fibrous structure 37 may beformed by performing, for example, spinning. The second fibrousstructure 37 may be obtained by, for example, preparing a solution, inwhich polyacrylonitrile is dispersed or dissolved inN,N′-dimethylformamide, as a spinning solution, and performing anelectrostatic spinning method using this solution. In place of theelectrostatic spinning method, a phase separation method, a phaseinversion method, a melt spinning method, a wet spinning method, a dryspinning method, a gel spinning method, a sol-gel method, a spraycoating method, or the like may be used.

After the second fibrous structure 37 is provided on the counterelectrode 22, the porous layer 33 is formed on the second fibrousstructure 37 (FIG. 4B). The porous layer 33 may be formed by, forexample, spinning a spinning solution, after adding a titanium oxide tothe spinning solution as the non-electrophoretic particle 33B andstirring this sufficiently. This makes it possible to form the porouslayer 33 in which the non-electrophoretic particle 33B is held in thefirst fibrous structure 33A. The spinning solution may be prepared by,for example, dispersing or dissolving polyacrylonitrile inN,N′-dimethylformamide as the first fibrous structure 33A. For example,an electrostatic spinning method may be used for the spinning.

It is preferable to use a spinning method for the formation of the firstfibrous structure 33A and the second fibrous structure 37. A method offorming a porous layer by perforating a polymeric film through use oflaser beam processing has been also proposed (see, for example, JapaneseUnexamined Patent Application Publication No. 2005-107146). In thismethod, however, only a large hole having an aperture of about 50 μm isformed, and it may be difficult to shield an electrophoretic particlecompletely by the porous layer.

Next, a solution (e.g., a UV-curable resin 38) in which a material ofthe partition 34 is dissolved in an organic solvent or the like asnecessary is prepared, and this solution is applied to the surface ofthe counter electrode 22 to fill the porous layer 33. Next, aplate-shaped supporting member 39 is disposed on the UV-curable resin 38(FIG. 4C). The supporting member 39 controls a coating thickness of theUV-curable resin 38, and it is possible to adjust the height of thepartition 34 through use of the supporting member 39. The supportingmember 39 may be configured of, for example, a material similar to thatof the supporting member 21, and have optical transparency. Thesupporting member 39 may have light reflectivity or light absorption.The UV-curable resin 38 may be, for example, a negative-type photoresist(a UV resin). A photosensitive resin material other than the UV-curableresin 38 may be used for the material of the partition 34.

After the supporting member 39 is provided on the UV-curable resin 38,patterning is performed by applying light L locally to the UV-curableresin 38 to form the partition 34 (FIG. 5A). Specifically, the light Lis applied to every formation region of the partition 34 (FIG. 4C) toperform exposure of the UV-curable resin 38 in each region. At thismoment, the light L passes through the supporting member 21 or thesupporting member 39 having the optical transparency to reach theUV-curable resin 38. The light L may be, for example, a laser beam in anultraviolet wavelength region, or the like. Use of a laser beam as thelight L makes a mask unnecessary, and makes it possible to expose adesirable region readily ad precisely. It is also possible to emit lamplight in an ultraviolet wavelength region, through use of a mask. Thelamp light and the laser beam may be used together.

Preferably, the light L may be applied from two directions, namely, thesupporting member 39 side and the supporting member 21 side facing thesupporting member 39. It is possible to maintain strength of thepartition 34 and to improve contrast, by thus applying the light L tothe UV-curable resin 38 from the two directions.

An amount of cured resin is largest in a part directly receiving curingenergy (e.g., light), and becomes smaller as a distance in which energypropagates becomes longer. In a case in which the light L is appliedfrom one direction, energy used to cure a range from one end to theother end of the partition 34 is necessary, and the light L of largeenergy is applied. At this moment, the width becomes large at the oneend (the side to which the light L is applied) of the partition 34. Inparticular, since the porous layer having high optical reflectanceinhibits propagation of light, the light L of large energy is necessaryand thus, the partition is formed to have a larger width. Further, when,for example, the density of the porous layer is increased to raise theoptical reflectance at the time of bright display, the light L of largerenergy is necessary. In other words, the opening section becomes small,and the contrast decreases. The energy of the light L may be reduced toform the partition 34 having a decreased overall width. In this case,however, the width of the other end of the partition 34 may become toosmall and thus, mechanical strength necessary for the partition 34 maynot be maintained.

In contrast, the partition 34 is allowed to be formed with the light Lof smaller energy, by application of the light L from the twodirections. Therefore, controlling the widths of the one end and theother end of the partition 34 is made easy, which makes it possible tomaintain the mechanical strength and to improve the contrast. Inaddition, it is also possible to raise the optical reflectance of theporous layer 33, by increasing the density of the porous layer 33, andthe like. The narrowed section 34C is formed at the partition 34, bythus applying the light L from the two directions.

After the application of the light L, the supporting member 39 isremoved, and the UV-curable resin 38 after the exposure is developed.The UV-curable resin 38 after being developed may be heated asnecessary. Thus, a non-exposed part of the UV-curable resin 38 isremoved and a remaining part (an exposed part) of the UV-curable resin38 becomes a film, to form the partition 34 incorporating a part of theporous layer 33. Here, the non-electrophoretic particle is not held inthe second fibrous structure 37. Therefore, it is possible to preventthe light L applied to the counter substrate 20 (the display surface)side from being affected by the non-electrophoretic particle, and toreduce the width W1 (FIG. 3A) of the partition 34 in the second fibrousstructure 37. This will be described below in detail.

FIG. 6A and FIG. 6B illustrate a process of manufacturing anelectrophoretic device according to a comparative example. Thiselectrophoretic device is not provided with the second fibrousstructure. In the process of manufacturing such an electrophoreticdevice, when light L is applied to a UV-curable resin 38 (FIG. 6A), thelight L diffuses at a surface of a porous layer 33 due to anon-electrophoretic particle having high optical reflectance. In otherwords, an amount of cured photosensitive resin in proximity to a countersubstrate 20 and an auxiliary member 39 increases (FIG. 6B), and a widthof each of both ends (widths W101 and W103) of a partition 134 increasesas illustrated in FIG. 7A. In particular, as the width W101 of thepartition 134 on a display surface side increases, an opening sectionbecomes small (FIG. 7B), and contrast decreases. The width W101 of thepartition 134 may be, for example, about 14.4 μm to about 15.2 μm.

In contrast, in the present embodiment, the second fibrous structure 37having the optical transparency covers the porous layer 33. In otherwords, the light L incident from the counter substrate 20 (the displaysurface) side enters the porous layer 33 after passing through thesecond fibrous structure 37 without being diffused. Therefore, it ispossible to reduce the width W1 in the second fibrous structure 37 ofthe partition 34, by suppressing the amount of cured photosensitiveresin in the second fibrous structure 37. This increases the regionwhere the optical properties change due to the movement of theelectrophoretic particle 32 caused by electrophoresis, thereby improvingthe contrast. The width W1 of the partition 34 formed on the sameconditions as those of the partition 134 of the comparative exampleexcept for provision of the second fibrous structure 37 may be about10.9 μm to about 11.0 μm. The light L is diffused at the surface of theporous layer 33, and the width W2 larger than the width W1 is formed.

After the partition 34 is formed, the counter substrate 20 and a releasemember 51 having the sealing layer 16 are disposed to face each otherwith the spacer 40 interposed therebetween. Next, a space between thecounter substrate 20 and the sealing layer 16 is filled with theinsulating liquid 31 in which the electrophoretic particles 32 aredispersed (FIG. 5B). The sealing layer 16 is then removed from therelease member 51, and fixed to the drive substrate 10 by the bondinglayer 15. In the drive substrate 10, the TFT 12, the protective layer13, and the pixel electrode 14 may be formed in this order on onesurface of the supporting member 11, through use of, for example, anexisting method. The display unit 1 is completed by going through theabove-described processes. It is also possible to manufacture thedisplay unit 1, using a Roll to Roll method.

In the display unit 1, in the initial state, all the electrophoreticparticles 32 dispersed in the insulating liquid 31 are arranged on aside close to the pixel electrode 14 (FIG. 1). At this moment, whenviewed from the counter substrate 20 side, the electrophoretic device 30is in such a state that the electrophoretic particles 32 are shielded bythe porous layer 33 and an image is not displayed.

When a pixel is selected by the TFT 12, and an electric field is appliedbetween the pixel electrode 14 and the counter electrode 22, theelectrophoretic particle 32 in the selected pixel passes through thepore 35 of the porous layer 33 and moves towards the counter electrode22, as illustrated in FIG. 8. At this moment, when the electrophoreticdevice 30 is viewed from the counter substrate 20 side, the porous layer33 is in such a state that a pixel of dark display that is shielded bythe electrophoretic particle 32 and a pixel of bright display that isnot shielded are both present. The pixel of dark display and the pixelof bright display cause the contrast, to display an image on the countersubstrate 20 side.

Here, the width W1 (FIG. 3A) of the partition 34 in the second fibrousstructure 37 is smaller than the width W2 of the part of the partition34, the part being closest to the second fibrous structure 37 in theporous layer 33 and thus, the opening section becomes wide. Therefore,the contrast improves.

As described above, in the electrophoretic device 30 of the presentembodiment, the partition 34 has the width W1 smaller than the width W2of the porous layer 33 in the second fibrous structure 37. Therefore,the contrast improves.

Further, the porous layer 33 is covered by the second fibrous structure37. Thus, the partition 34 having the width W1 is allowed to be readilyformed. Furthermore, the electrophoretic particle 32 after moving to thecounter substrate 20 side at the time of dark display is held in thesecond fibrous structure 37 having the optical transparency. Therefore,the optical reflectance at the time of dark display is allowed to bereduced by shielding the porous layer 33 sufficiently. Accordingly, thecontrast further improves.

In addition, the partition 34 includes the light transmissive material,and also incorporates the part of the porous layer 33. Thus, thecontrast is allowed to be improved by increasing the optical reflectanceat the time of bright display.

APPLICATION EXAMPLES Display Unit

Next, application examples of the display unit 1 will be described. Thedisplay unit 1 may be mounted on, for example, the following electronicapparatuses. However, each of configurations of the electronicapparatuses to be described below is a mere example and therefore, theconfiguration thereof is modifiable as appropriate.

Application Example 1

FIGS. 9A and 9B each illustrate an appearance of an electronic book.This electronic book may include, for example, a display section 110, anon-display section 120, and an operation section 130. It is to be notedthat the operation section 130 may be provided either on a front surfaceof the non-display section 120 as illustrated in FIG. 9A, or on a topsurface of the non-display section 120 as illustrated in FIG. 9B. Thedisplay section 110 is configured using the display unit 1. It is to benoted that the display unit 1 may be mounted on a PDA (Personal DigitalAssistant) having a configuration similar to that of the electronic bookillustrated in FIGS. 9A and 9B.

Application Example 2

FIG. 10 illustrates an appearance of a television receiver. Thistelevision receiver may have, for example, an image-display screensection 200 that includes a front panel 210 and a filter glass 220. Theimage-display screen section 200 is configured using the display unit 1.

Application Example 3

FIG. 11 illustrates an appearance of a tablet personal computer. Thistablet personal computer may include, for example, a touch panel section310 and a housing 320. The touch panel section 310 is configured usingthe display unit 1.

Application Example 4

FIGS. 12A and 12B each illustrate an appearance of a digital camera.FIG. 12A illustrates a front face, and FIG. 12B illustrates a rear face.This digital camera may include, for example, a flash emitting section410, a display section 420, a menu switch 430, and a shutter release440. The display section 420 is configured using the display unit 1.

Application Example 5

FIG. 13 illustrates an appearance of a laptop computer. This laptopcomputer may include, for example, a main body section 510, a keyboard520 provided to enter characters and the like, and a display section 530displaying an image. The display section 530 is configured using thedisplay unit 1.

Application Example 6

FIG. 14 illustrates an appearance of a video camera. This video cameramay include, for example, a main body section 610, a lens 620 disposedon a front face of the main body section 610 to shoot an image of asubject, a start/stop switch 630 used in shooting, and a display section640. The display section 640 is configured using the display unit 1.

Application Example 7

FIGS. 15A and 15B each illustrate appearances of a mobile phone. FIG.15A illustrates a front face, a left side face, a right side face, a topface, and an undersurface of the mobile phone in a closed state. FIG.15B illustrates a front face and a side face of the mobile phone in anopen state. This mobile phone may be, for example, a unit in which anupper housing 710 and a lower housing 720 are connected by a couplingsection (a hinge section) 730, and include a display 740, a sub-display750, a picture light 760, and a camera 770. The display 740 or thesub-display 750 is configured using the display unit 1.

Example

Next, an Example of the present technology will be described.

Table 1 provides a comparison between contrast of an electrophoreticdevice (an experimental example 1) in which the porous layer was coveredwith the second fibrous structure and contrast of an electrophoreticdevice (an experimental example 2) configured without providing thesecond fibrous structure. Polyacrylonitrile was used for the firstfibrous structure of each of the experimental examples 1 and 2, and forthe second fibrous structure of the experimental example 2. A density ofelectrophoretic particles in an insulating liquid was 1.25% in both ofthe experimental examples 1 and 2. At the time of spinning, the firstfibrous structure had a thickness of 26 μm (the experimental examples 1and 2), and the second fibrous structure had a thickness of 5 μm.

TABLE 1 Optical Optical Reflectance in Reflectance in ExperimentalSecond Fibrous Bright Display Dark Display Examples Structure (%) (%)Contrast 1 Present 49.5 2.39 20.7 2 Absent 51.1 4.3 11.9

As apparent from these results, by providing the second fibrousstructure, the opening section is increased, and a region where theelectrophoretic particles are freely movable by electrophoresis expands.In addition, the electrophoretic particles shield the porous layereffectively. In other words, the optical reflectance in dark displaydrops considerably (from 4.3% to 2.39%), thereby allowing the contrastto be improved.

The present technology has been described above with reference to someembodiment and Example, but is not limited thereto and may be variouslymodified. For example, the electrophoretic device according to anembodiment of the present technology may be applied to not only adisplay unit but other types of electronic apparatuses.

Further, the above-described embodiment and the like have been describedwith reference to the case in which the dark display is performed by theelectrophoretic particles and the bright display is performed by theporous layer. However, the dark display may be performed by the porouslayer and the bright display may be performed by the electrophoreticparticles, as long as the width W1 is formable in the partition 34.

Furthermore, the above-described embodiment and the like have beendescribed with reference to the case in which the top of the porouslayer 33 is directly covered with the second fibrous structure 37.However, one or a plurality of structures may be arranged between theporous layer 33 and the second fibrous structure 37, as long as thesecond fibrous structure 37 is provided at a position closest to thedisplay surface.

In addition, the case in which the pitch of the partitions 34 and thatof the pixels do not agree with each other is illustrated in FIG. 1, butthese may agree with each other.

Still further, the above-described embodiment and the like have beendescribed with reference to the case in which the drive substrate 10 andthe sealing layer 16 are fixed using the bonding layer 15 interposedtherebetween. However, the sealing layer 16 may be directly fixed to thedrive substrate 10.

In addition, the above-described embodiment and the like have beendescribed with reference to the method of filling the insulating liquid31, after the counter substrate 20 and the sealing layer 16 are disposedto face each other, but the display unit 1 may be manufactured by othermethod. For example, the counter substrate 20 may be disposed to facethe sealing layer 16, after the insulating liquid 31 is applied to thecounter substrate 20 on which the porous layer 33 is formed.

Furthermore, the technology encompasses any possible combination of someor all of the various embodiments described herein and incorporatedherein.

It is possible to achieve at least the following configurations from theabove-described example embodiments of the disclosure.

(1) An electrophoretic device, including:

-   -   a porous layer including a first fibrous structure and a        non-electrophoretic particle held in the first fibrous        structure;    -   an electrophoretic particle configured to move through a space        formed at the porous layer;    -   a second fibrous structure covering the porous layer; and    -   a partition provided from the porous layer to the second fibrous        structure.        (2) The electrophoretic device according to (1), wherein a        width, in the second fibrous structure, of the partition is        smaller than a width of a part of the partition in the porous        layer, the part being closest to the second fibrous structure.        (3) The electrophoretic device according to (1) or (2), wherein        a width, in the second fibrous structure, of the partition is        smaller than a width, in the porous layer, of the partition.        (4) The electrophoretic device according to any one of (1) to        (3), wherein the second fibrous structure is disposed between        the first fibrous structure and a display surface.        (5) The electrophoretic device according to any one of (1) to        (4), wherein the non-electrophoretic particle has optical        reflectance that is higher than optical reflectance of the        electrophoretic particle.        (6) The electrophoretic device according to any one of (1) to        (5), wherein the partition includes a photocurable resin.        (7) The electrophoretic device according to any one of (1) to        (6), wherein the partition includes a narrowed section in the        porous layer.        (8) The electrophoretic device according to any one of (1) to        (7), wherein

the porous layer, the electrophoretic particle, the second fibrousstructure, and the partition are provided in an insulating liquid, and

a difference between a refractive index of the insulating liquid and arefractive index of the second fibrous structure is smaller than adifference between the refractive index of the insulating liquid and arefractive index of the porous layer.

(9) The electrophoretic device according to any one of (1) to (8),wherein the partition includes a light transmissive material, andincorporates a part of the porous layer.(10) An electrophoretic device, including:

a porous layer including a fibrous structure and a non-electrophoreticparticle held in the fibrous structure;

an electrophoretic particle configured to move through a space formed atthe porous layer; and

a partition provided from inside of the porous layer to outside of theporous layer, wherein a width of a part of the partition, the part beingon the outside of the porous layer, is smaller than a width of a part ofthe partition in the porous layer, the part being closest to theoutside.

(11) A display unit provided with an electrophoretic device, theelectrophoretic device including:

a porous layer including a first fibrous structure and anon-electrophoretic particle held in the first fibrous structure;

an electrophoretic particle configured to move through a space formed atthe porous layer;

a second fibrous structure covering the porous layer; and

a partition provided from the porous layer to the second fibrousstructure.

(12) A display unit provided with an electrophoretic device, theelectrophoretic device including:

a porous layer including a fibrous structure and a non-electrophoreticparticle held in the fibrous structure;

an electrophoretic particle configured to move through a space formed atthe porous layer; and

a partition provided from inside of the porous layer to outside of theporous layer, wherein a width of a part of the partition, the part beingon the outside of the porous layer, is smaller than a width of a part ofthe partition in the porous layer, the part being closest to theoutside.

(13) An electronic apparatus with a display unit, the display unit beingprovided with an electrophoretic device, the electrophoretic deviceincluding:

a porous layer including a first fibrous structure and anon-electrophoretic particle held in the first fibrous structure;

an electrophoretic particle configured to move through a space formed atthe porous layer;

a second fibrous structure covering the porous layer; and

a partition provided from the porous layer to the second fibrousstructure.

(14) An electronic apparatus with a display unit, the display unit beingprovided with an electrophoretic device, the electrophoretic deviceincluding:

a porous layer including a fibrous structure and a non-electrophoreticparticle held in the fibrous structure;

an electrophoretic particle configured to move through a space formed atthe porous layer; and

a partition provided from inside of the porous layer to outside of theporous layer, wherein a width of a part of the partition, the part beingon the outside of the porous layer, is smaller than a width of a part ofthe partition in the porous layer, the part being closest to theoutside.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations, and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

1. An electrophoretic device, comprising: a porous layer configured tohave a first fibrous structure including a non-electrophoretic particleand an electrophoretic particle; a second fibrous structure configuredto cover the porous layer; and wherein a width, in the second fibrousstructure, of the partition is smaller than a width of a part of thepartition in the porous layer, the part being closest to the secondfibrous structure.
 2. The electrophoretic device according to claim 1,wherein the porous layer, the electrophoretic particle, the secondfibrous structure, and the partition are provided in an insulatingliquid, and a difference between a refractive index of the insulatingliquid and a refractive index of the second fibrous structure is smallerthan a difference between the refractive index of the insulating liquidand a refractive index of the porous layer.
 3. The electrophoreticdevice according to claim 1, wherein a width, in the second fibrousstructure, of the partition is smaller than a width, in the porouslayer, of the partition.
 4. The electrophoretic device according toclaim 1, wherein the second fibrous structure is disposed between thefirst fibrous structure and a display surface.
 5. The electrophoreticdevice according to claim 1, wherein the non-electrophoretic particlehas optical reflectance that is higher than optical reflectance of theelectrophoretic particle.
 6. The electrophoretic device according toclaim 1, wherein the partition includes a photocurable resin.
 7. Theelectrophoretic device according to claim 6, wherein the partitionincludes a narrowed section in the porous layer.
 8. The electrophoreticdevice according to claim 1, wherein the partition includes a lighttransmissive material, and incorporates a part of the porous layer.
 9. Adisplay unit provided with an electrophoretic device, theelectrophoretic device comprising: a porous layer configured to have afirst fibrous structure including a non-electrophoretic particle and anelectrophoretic particle; a second fibrous structure configured to coverthe porous layer; and wherein a width, in the second fibrous structure,of the partition is smaller than a width of a part of the partition inthe porous layer, the part being closest to the second fibrousstructure.
 10. The display unit according to claim 9, wherein the porouslayer, the electrophoretic particle, the second fibrous structure, andthe partition are provided in an insulating liquid, and a differencebetween a refractive index of the insulating liquid and a refractiveindex of the second fibrous structure is smaller than a differencebetween the refractive index of the insulating liquid and a refractiveindex of the porous layer.
 11. The display unit according to claim 9,wherein a width, in the second fibrous structure, of the partition issmaller than a width, in the porous layer, of the partition.
 12. Thedisplay unit according to claim 9, wherein the second fibrous structureis disposed between the first fibrous structure and a display surface.13. The display unit according to claim 9, wherein thenon-electrophoretic particle has optical reflectance that is higher thanoptical reflectance of the electrophoretic particle.
 14. The displayunit according to claim 9, wherein the partition includes a photocurableresin.
 15. The display unit according to claim 14, wherein the partitionincludes a narrowed section in the porous layer.
 16. The display unitaccording to claim 9, wherein the partition includes a lighttransmissive material, and incorporates a part of the porous layer.